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Monday, March 20, 2017

Beijing ‘Severe Haze’ Could Be 50% More Frequent Under Climate Change

In December last year, Beijing and the surrounding area was engulfed in a thick haze that lasted for days. In response, the Chinese government declared a red alert, closing nurseries and schools, taking vehicles off the road, and telling residents to stay indoors.These “airpocalypse” winter haze events have become something of a regular occurrence in the Chinese capital in recent years. Similar events covered the city in December 2015 and January 2013.In a new study, just published in Nature Climate Change, we show that the increased frequency of Beijing winter severe haze is not just due to pollution from China’s rapid economic development, but also because of changes in wind patterns caused by a warming climate.And, as climate change continues, severe winter haze events could become 50% more frequent and 80% longer in duration by the second half of this century.Particulate matterDespite stringent emission controls implemented by the Chinese government, the frequency of Beijing winter severe haze events has been increasing in recent years.During these episodes, air pollution from vehicles and industry envelops the capital city in a toxic fog. The cocktail of soot, dirt, dust and smoke in the air is harmful to human health and the environment, and causes massive disruption to economic activities.Of particular concern are the levels of tiny particulate matter known as “PM2.5” pollutants, so-called because they’re smaller than 2.5 micrometers in diameter. That’s about one thirtieth of the average width of a human hair. When inhaled, these minuscule particles can penetrate deep into the lungs, affecting the respiratory and circulatory systems, with detrimental effects on the cardiovascular, immune, and nervous systems.In the winter haze event of January 2013, for example, average levels of PM2.5 for the month exceeded 130 μg m-3 (micrograms per cubic meter) in 30 cities across 16 provinces. World Health Organisation guidelines recommend the PM2.5 levels for any 24-hour period shouldn’t exceed 25 μg m-3. In December last year, Beijing and the surrounding area was engulfed in a thick haze that lasted for days. In response, the Chinese government declared a red alert, closing nurseries and schools, taking vehicles off the road, and telling residents to stay indoors.Read more at https://www.carbonbrief.org/beijing-severe-haze-could-be-fifty-per-cent-more-frequent-under-climate-change Click to Enlarge.